1. Field of the Invention
The invention relates to an illuminance device. More particularly, the invention relates to an illuminance device adapted to a projection system.
2. Description of Related Art
An ultra high pressure mercury lamp is generally used as a light source of a present projector, and the ultra high pressure mercury lamp is one kind of a gas discharge lamp. Since an operation temperature of the ultra high pressure mercury lamp is very high, during operation, the ultra high pressure mercury lamp has to be cooled down to avoid burning damage.
During a cooling process of the ultra high pressure mercury lamp, a bulb of a burner of the ultra high pressure mercury lamp has to be maintained to a specific high temperature range, while the temperature of other parts (for example, welding points among elements) of the burner cannot be too high. If these temperature requirements cannot be satisfied, a lifespan of the ultra high pressure mercury lamp is decreased.
References related to the light source cooling include Taiwan patent No. I235281 and I261858, and U.S. Pat. No. 6,976,760. Other references related to the light source cooling include Taiwan patent application publication No. 200725158 and 200732821, Taiwan patent No. M278917 and U.S. Pat. No. 6,558,004.